Refrigerant system with reheat refrigerant circuit

ABSTRACT

A refrigerant system is provided that includes a cooling refrigerant circuit, a reheat refrigerant circuit, an evaporator fan, and a controller. The evaporator fan forces indoor air in a first direction and a second direction. The indoor air passes across the evaporator before the reheat coil, in the first direction, but passes across the reheat coil before the evaporator, in the second direction. The controller, when in a conventional cooling mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is not in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the first direction. Conversely, the controller, when in a defrost mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the second direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure is related to refrigerant systems. Moreparticularly, the present disclosure is related to refrigerant systemshaving defrost functionality provided by a reheat refrigerant circuit.

2. Description of Related Art

Refrigerant systems are utilized to control the temperature and/orhumidity of air in various environments to be conditioned. In a typicalrefrigerant system operating in a conventional cooling mode, arefrigerant is compressed in a compressor and delivered to a heatrejection heat-exchanger (or, in many cases, an outdoor heat-exchanger).In the heat rejection heat-exchanger, heat is exchanged between outsideambient air and the compressed refrigerant, to remove heat from thecompressed refrigerant.

From the heat rejection heat-exchanger, the refrigerant passes to anexpansion device, in which the refrigerant is expanded to a lowerpressure and lower temperature, and then to an evaporator (or, intypical air conditioning installations, an indoor heat-exchanger). Inthe evaporator, heat is exchanged between the now cooled lower pressurerefrigerant and the indoor air, to remove heat from the indoor air. Inthis manner, the evaporator cools the air that is being supplied to theconditioned environment.

In addition, as the temperature of the conditioned air is reduced,moisture is also often taken out of the conditioned air. In this manner,refrigerant systems also control the humidity level in the conditionedenvironment.

In some cases, while the system is operating in the conventional coolingmode, the temperature level of the conditioned air necessary to providethe desired humidity level is lower than the desired temperature of theconditioned air. Thus, many refrigerant systems include a reheat coil orheat-exchanger (hereinafter “coil”) that is placed in the conditionedair stream downstream of the evaporator. In this manner, the reheat coilreheats the conditioned air after the air has been conditioned (e.g.,cooled and dehumidified) in the evaporator.

It is also not uncommon for the moisture removed from the air tocondense and frequently freeze on the external surfaces of theevaporator, which reduces the efficiency of the refrigerant system, andcould also result in a refrigerant system malfunction. As such, manyrefrigerant systems require specialized defrost systems and equipment(such as, for instance, electric heaters), which increase the cost andcomplexity of the refrigerant system.

Accordingly, there is continuing need for refrigerant systems andmethods of controlling such systems that defrost the evaporator whileovercoming one or more of the aforementioned and other deleteriouseffects of the prior art.

BRIEF SUMMARY OF THE INVENTION

A refrigerant system is provided that includes a cooling refrigerantcircuit, a reheat refrigerant circuit, an evaporator fan, and acontroller. The cooling refrigerant circuit includes an evaporator. Thereheat refrigerant circuit includes a reheat coil. The evaporator fan iscapable of forcing indoor air in a first direction and a seconddirection. The indoor air passes across the evaporator before the reheatcoil in the first direction but passes across the reheat coil before theevaporator in the second direction. The controller, when in aconventional cooling mode, controls the reheat refrigerant circuit sothat the reheat refrigerant circuit is not in fluid communication withthe cooling refrigerant circuit and controls the evaporator fan to forcethe indoor air in the first direction. Conversely, the controller, whenin a defrost mode, controls the reheat refrigerant circuit so that thereheat refrigerant circuit is in fluid communication with the coolingrefrigerant circuit and controls the evaporator fan to force the indoorair in the second direction. In the conventional dehumidification modethe controller controls the reheat refrigerant circuit so that thereheat refrigerant circuit is in fluid communication with the coolingrefrigerant circuit and controls the evaporator fan to force the indoorair in the first direction.

In some embodiments, the refrigerant system includes a coolingrefrigerant circuit, a reheat refrigerant circuit, an evaporator fan,and a controller. The cooling refrigerant circuit includes anevaporator. The reheat refrigerant circuit includes a reheat coil. Theevaporator fan rotates in a first rotational direction to force indoorair in a first direction and rotates in a second rotational direction toforce the indoor air in a second direction. The evaporator is positionedupstream of the reheat coil in the first direction. The controlleroperates the refrigerant system in a conventional cooling mode when thereheat refrigerant circuit is not in fluid communication with thecooling refrigerant circuit and the evaporator fan rotates in the firstrotational direction. The controller also operates the refrigerantsystem in a defrost mode when the reheat refrigerant circuit is in fluidcommunication with the cooling refrigerant circuit and the evaporatorfan rotates in the second rotational direction. The controller operatesthe refrigerant system in a conventional dehumidification mode when thereheat refrigerant circuit is in fluid communication with the coolingrefrigerant circuit and the evaporator fan rotates in the firstrotational direction.

In other embodiments, the refrigerant system includes a coolingrefrigerant circuit, a reheat refrigerant circuit, an evaporator fanthat rotates in a single rotational direction, one or more dampers, anda controller. The cooling refrigerant circuit includes an evaporator.The reheat refrigerant circuit includes a reheat coil. The dampers arein a flow path of the indoor air and have two positions. The firstposition forces the indoor air in a first direction so the indoor airpasses across the evaporator before the reheat coil. The second positionforces the indoor air in a second direction so the indoor air passesacross the reheat coil before the evaporator. The controller operatesthe refrigerant system in a conventional cooling mode when the reheatrefrigerant circuit is not in fluid communication or at least partiallyisolated from the cooling refrigerant circuit and the one or moredampers are in the first position. The controller also operates therefrigerant system in a defrost mode when the reheat refrigerant circuitis in fluid communication with the cooling refrigerant circuit and theone or more dampers are in the second position. The controller operatesthe refrigerant system in a conventional dehumidification mode when thereheat refrigerant circuit is in fluid communication with the coolingrefrigerant circuit and the one or more dampers are in the firstposition.

The above-described and other features and advantages of the presentdisclosure will be appreciated and understood by those skilled in theart from the following detailed description, drawings, and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic depiction of an exemplary embodiment of arefrigerant system according to the present disclosure operating in anormal or conventional cooling mode;

FIG. 2 is schematic depiction of the refrigerant system of FIG. 1operating in a reheat or conventional dehumidification mode;

FIG. 3 is schematic depiction of the refrigerant system of FIG. 1operating in a defrost mode;

FIG. 4 is schematic depiction of an alternate embodiment of therefrigerant system of FIG. 1 operating in the normal mode and the reheatmode; and

FIG. 5 is schematic depiction of the refrigerant system of FIG. 4operating in the defrost mode.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, and in particular to FIG. 1, an exemplaryembodiment of a refrigerant system according to the present disclosure,generally indicated by reference numeral 10, is shown.

Refrigerant system 10 includes a cooling refrigerant circuit 12, areheat refrigerant circuit 14, and a bypass refrigerant circuit 16.Refrigerant system 10 is configured to utilize reheat refrigerantcircuit 14 and bypass refrigerant circuit 16 during the defrosting ofthe evaporator.

Cooling refrigerant circuit 12 includes a compressor 18, a heatrejection heat-exchanger 20, an expansion device 22, and an evaporator24, all in fluid communication with one another in a known manner toprovide, for instance, a cooling or heating function using a knownrefrigerant (not shown). Refrigerant system 10 further includes a heatrejection heat-exchanger fan 26, an evaporator fan 28, and a refrigerantsystem controller 30.

Reheat refrigerant circuit 14 includes a reheat coil 32 and a firstreheat valve 34-1 and a second reheat valve 34-2, while bypass circuit16 includes a bypass valve 36. The first reheat valve 34-1 typically isa three-way valve and the second reheat valve 34-2 is a check valve.

Controller 30 is in electrical communication with the compressor 18,heat rejection heat-exchanger fan 26, evaporator fan 28, first reheatvalve 34-1, and bypass valve 36. In some embodiments, the controller 30can also be in electrical communication with the compressor 18,expansion device 22 and/or second reheat valve 34-2. In this manner, thecontroller 30 is configured to control the operation of the variouscomponents of the refrigerant system 10.

The controller 30 is configured to operate the refrigerant system 10 ina normal or conventional cooling mode (FIG. 1), a reheat or conventionaldehumidification mode (FIG. 2), and defrost mode (FIG. 3). Refrigerantsystem 10 operates in the defrost mode without the need for additionalor specialized defrosting devices, such as, for example, an electricheater. Rather, it has been determined by the present disclosure thatthe refrigerant system 10 can provide the defrost mode of operation bysimply making use of the existing components of the reheat refrigerantcircuit 14. More particularly, the refrigerant system 10 is configuredto control evaporator fan 28 to force air in a first normal directionduring the normal mode and the reheat mode of operation, but in a secondopposite direction during the defrost mode of operation.

The normal mode of operation for the refrigerant system 10 is describedwith reference to FIG. 1.

Here, the compressor 18 draws in a low-pressure refrigerant 40, in avapor form and compresses this low-pressure vapor refrigerant into ahigh pressure and temperature refrigerant 42. From the compressor 18,the vapor refrigerant flows to the heat rejection heat-exchanger 20. Thecontroller 30 controls the bypass valve 36 to a closed position so thatrefrigerant 42 flows through the heat rejection heat-exchanger 20 andnot through the bypass refrigerant circuit 16. Thus, the controller 30controls the bypass valve 36 so that the bypass refrigerant circuit 16is not in fluid communication with cooling refrigerant circuit 12 duringthe normal mode of operation.

The heat rejection heat-exchanger 20 acts as a condenser, in thesubcritical cycle, or as a gas cooler, in a transcritical cycle, whereduring heat transfer interaction with a secondary fluid, such as outsideor ambient air 44 that is forced across the heat rejectionheat-exchanger 20 by the heat rejection heat-exchanger fan 26. In thismanner, in the subcritical applications, the vapor refrigerant 42 isdesuperheated to the point where it condenses to a liquid refrigerant 46and is typically subcooled, or just simply cooled from the thermodynamicstate 42 to the thermodynamic state 46, in the transcriticalapplications. As known, a liquid pump may substitute the fan 26 to pumpsecondary loop liquid performing heat transfer interaction in the heatrejection heat-exchanger 20 instead of the outside or ambient air 44.

The refrigerant 46 exits heat rejection heat-exchanger 20 and flows tothe expansion device 22. The controller 30 controls the first reheatvalve 34-1 to a closed position so that the refrigerant 46 flows throughthe expansion device 22 and, not, through the reheat refrigerant circuit14. Thus, the controller 30 controls the first reheat valve 34-1 so thatthe reheat refrigerant circuit 14 is not in fluid communication with thecooling refrigerant circuit 12 during the normal or conventional coolingmode of operation.

In some embodiments, the second reheat valve 34-2 can be a check valvethat ensures the refrigerant 46 does not enter the reheat refrigerantcircuit 14. In other embodiments, the second reheat valve 34-2 can be inelectrical communication with the controller 30, which controls thesecond reheat valve 34-2 to the closed position during the normal modeof operation to ensure that refrigerant 46 does not enter the reheatrefrigerant circuit 14.

The expansion device 22 expands refrigerant 46 into a lower pressure,lower temperature, two-phase mixture refrigerant 48, which flows intothe evaporator 24. In some embodiments, the expansion device 22 is athermostatic expansion valve or a fixed restriction expansion device,while in other embodiments the expansion device can be an electronicexpansion device (EXV) in electrical communication with the controller30.

The evaporator 24 acts as a heat accepting heat-exchanger where heattransfer interaction occurs between the refrigerant and the indoor air50 that is forced across the evaporator 24 by the evaporator fan 28 in afirst direction 54. In this manner, the refrigerant 48 is evaporatedback into a low pressure vapor refrigerant 40, while the indoor air 50is cooled and usually dehumidified to provide the conditioned air 52that is supplied to a climate-controlled space or zone. The vaporrefrigerant 40, which is typically in a thermodynamic superheated state,then flows from the evaporator 24 back to the compressor 18.

As can be seen, reheat coil 32 is positioned downstream, with respect tothe flow of indoor air 50 in the first direction 54 induced by theevaporator fan 28. However, since the reheat valves 34-1, 34-2 are inthe closed position, the flow of conditioned air 52 through the reheatcoil 32 does not result in any further conditioning or reheating of thisconditioned air.

Accordingly, during the normal mode of operation for the refrigerantsystem 10, the controller 30 activates the compressor 18, activates theheat rejection heat-exchanger fan 26, closes the bypass valve 36, closesthe reheat valves 34-1 and 34-2, activates, when necessary, theexpansion valve 22, and activates the evaporator fan 28 to force theindoor air 50 across the evaporator 24 and the reheat coil 32 in thefirst direction. Since the controller 30 controls the evaporator fan 28to force indoor air 50 in the first direction 54, the indoor air isforced first across the evaporator 24 then across the reheat coil 32.

In the embodiment illustrated in FIG. 1, the refrigerant system 10 isconfigured to force the indoor air 50 in the first direction 54 bycontrolling the evaporator fan 28 to rotate in a first rotationaldirection 56. It has to be pointed out that the evaporator fan 28 may beof a variable speed type so that the controller 30 may also control thespeed of the evaporator fan 28 if desired.

The reheat mode of operation for the refrigerant system 10 is describedwith reference to FIG. 2.

Generally, the refrigerant system 10 operates in substantially the samemanner in the reheat mode as in the normal mode, except that thecontroller 30 controls the first reheat valve 34-1 to an open positionso that the refrigerant 46 flows first through the reheat refrigerantcircuit 14 and only then through the expansion device 22. Thus, thecontroller 30 controls the first reheat valve 34-1 so that the reheatrefrigerant circuit 14 is in fluid communication with the coolingrefrigerant circuit 12 during the reheat mode of operation.

In use, the compressor 18 draws in a low pressure refrigerant 40, in avapor form and compresses this low pressure vapor refrigerant into ahigh pressure and temperature refrigerant 42. From the compressor 18,the vapor refrigerant flows to the heat rejection heat-exchanger 20.

The controller 30 may control the bypass valve 36 to a closed orpartially/fully open position so that the vapor high pressure and hightemperature refrigerant 42 can flow through the heat rejectionheat-exchanger 20 and, not, the bypass refrigerant circuit 16, orthrough both the heat rejection heat-exchanger 20 and bypass refrigerantcircuit 16. Thus, the controller 30 controls the bypass valve 36 so thatthe bypass refrigerant circuit 16 may or may not be in fluidcommunication with the cooling refrigerant circuit 12 during the reheatmode of operation. As stated above, depending on the dehumidificationdemands in the climate-controlled space, in some embodiments, thecontroller 30 can control the bypass valve 36 to a partially openposition so that a portion of refrigerant 42 flows through the heatrejection heat-exchanger 20 and a remaining portion flows through thebypass refrigerant circuit 16.

The heat rejection heat-exchanger 20 acts as a condenser, in asubcritical cycle, or as a gas cooler, in a transcritical cycle, whereduring heat transfer interaction with outside or ambient air 44 that isforced across the heat rejection heat-exchanger 20 by the heat rejectionheat-exchanger fan 26. In this manner, in the subcritical applications,the vapor refrigerant 42 is desuperheated to the point where itcondenses to a liquid refrigerant 46 and is typically subcooled, or justsimply cooled from the thermodynamic state 42 to the thermodynamic state46, in the transcritical applications. Once again, a liquid pump maysubstitute the fan 26 to pump secondary loop liquid performing heattransfer interaction in the heat rejection heat-exchanger 20 instead ofthe outside or ambient air 44.

The refrigerant 46 exits the heat rejection heat-exchanger 20 and flowsto the first reheat valve 34-1. The controller 30 controls the firstreheat valve 34-1 to an open position so that the refrigerant 46 flowsthrough the reheat coil 32, through the second reheat valve 34-2, andonly then into the expansion device 22.

In some embodiments, the second reheat valve 34-2 can be a check valvethat allows the refrigerant 46 to exit the reheat refrigerant circuit 14back into the cooling refrigerant circuit 12. In other embodiments, thesecond reheat valve 34-2 can be in electrical communication with thecontroller 30, which controls the second reheat valve 34-2 to the openposition during the reheat mode of operation to allow the refrigerant 46to reenter the cooling refrigerant circuit 12.

Since the refrigerant 46 has not yet been expanded by the expansiondevice 22, the heat capacity of the refrigerant 46 can be used to reheatthe conditioned air 52 in the manner discussed in more detail below.

The expansion device 22 expands the refrigerant 46 into a low pressure,low temperature, two-phase mixture refrigerant 48 and flows into theevaporator 24. The evaporator 24 acts as a heat accepting heat-exchangerwhere heat transfer interaction occurs between the refrigerant and theindoor air 50 that is forced across the evaporator 24 by the evaporatorfan 28. In this manner, the refrigerant 48 is evaporated back into a lowpressure vapor refrigerant 40, while the indoor air 50 is cooled andusually dehumidified to provide the conditioned air 52 that is suppliedto a climate-controlled space or zone. The vapor refrigerant 40, whichis typically in the superheated thermodynamic state, then flows from theevaporator 24 back to the compressor 18.

As can be seen, the reheat coil 32 is positioned downstream, withrespect to the flow of indoor air 50 induced by the evaporator fan 28 inthe first direction 54. Since the refrigerant 46 is flowing through thereheat coil 32, the flow of conditioned air 52 through the reheat coil32 results in the reheat coil 32 acting as a heat rejectingheat-exchanger, where heat transfer is taking place from the refrigerantto air re-heating the air, and where the conditioned air 52 is forcedacross the reheat coil 32 by the evaporator fan 28. In this manner, theconditioned air 52 can be reheated to a desired temperature by thereheat coil 32 while maintaining the desired humidity by the evaporator24 to provide a reheated air 58.

Accordingly, during the reheat mode of operation for the refrigerantsystem 10, the controller 30 activates the compressor 18, activates theheat rejection heat-exchanger fan 26, controls the bypass valve 36,opens the first reheat valve 34-1, activates, when necessary, theexpansion valve 22, and activates the evaporator fan 28 to force theindoor air 50 across the evaporator 24 and the reheat coil 32 in thefirst direction 54. Thus, the controller 30 controls the evaporator fan28 to force the air in the first direction 54 so that the indoor air 50is forced first across the evaporator 24 then across the reheat coil 32to provide the reheated air 58.

The refrigerant system 10 is configured, in the embodiment illustratedin FIG. 2, to force the indoor air 50 in the first direction 54 bycontrolling the evaporator fan 28 to rotate in the first rotationaldirection 56.

It has to be recognized that many reheat circuits schematics are knownin the air conditioning art. Therefore, the FIG. 2 schematic isexemplary, and any refrigerant system incorporating any other reheatcircuit configuration could equally benefit from the disclosure.

The defrost mode of operation for the refrigerant system 10 is describedwith reference to FIG. 3.

Generally, the refrigerant system 10 operates in substantially the samemanner in the defrost mode as in the reheat mode, except that thecontroller 30 preferably controls the bypass valve 36 to an openposition so that at least a portion of the high pressure and temperaturerefrigerant 42 flows through the bypass refrigerant circuit 16 insteadof flowing through the heat rejection heat-exchanger 20 and reverses thedirection of flow of the indoor air 50 across the evaporator 24 from afirst direction 54 (FIGS. 1 and 2) to a second direction 60 (FIG. 3).Further, the bypass refrigerant circuit 16 can be designed such thatpredominantly all the vapor refrigerant 42 flows through the bypassrefrigerant circuit 16, or alternatively, a shutoff solenoid valve (notshown) can be placed upstream of the heat rejection heat-exchanger 20 toprevent any flow of the vapor refrigerant 42 through the heat rejectionheat-exchanger 20.

During the defrost mode of operation, the compressor 18 draws in the lowpressure refrigerant 40, in a vapor form and compresses this lowpressure vapor refrigerant into the high pressure and high temperaturerefrigerant 42. From the compressor 18, the vapor refrigerant 42 flowstowards the heat rejection heat-exchanger 20 and the bypass refrigerantcircuit 16.

The controller 30 preferably controls the bypass valve 36 to the openposition so that at least a portion of the vapor refrigerant 42 does notflow through heat rejection heat-exchanger 20 but rather flows throughthe bypass refrigerant circuit 16. Further, the controller 30 can, insome embodiments, control the heat rejection heat-exchanger fan 26 to anoff state to prevent any active heat exchange between the refrigerantand ambient air in the heat rejection heat-exchanger 20. In this manner,the controller 30 preferably places the bypass refrigerant circuit 16 influid communication with the cooling refrigerant circuit 12 during thedefrost mode of operation so that the high pressure and high temperaturerefrigerant 42 flows into the reheat refrigerant circuit 14 providinggreater heat capacity during the defrost mode of operation.

However, in some embodiments, the controller 30 can control the bypassvalve 36 to a partially open position so that a portion of the vaporrefrigerant 42 flows through heat rejection heat-exchanger 20 and aremaining portion flows through bypass circuit 16. Further, thecontroller 30 can, in some embodiments, control the heat rejectionheat-exchanger fan 26 to an off state to prevent any active heatexchange between the refrigerant and ambient air in the heat rejectionheat-exchanger 20. Also, it has to be noted that, under somecircumstances, such as excessive refrigerant charge migration at someenvironmental conditions, the controller 30 may control the bypass valve36 to a closed position.

The high pressure and temperature refrigerant 42A exits the bypassrefrigerant circuit 16 and/or the heat rejection heat-exchanger 20 andflows to the first reheat valve 34-1. The controller 30 controls thefirst reheat valve 34-1 to the open position so that the high pressureand temperature refrigerant 42A flows through the reheat coil 32,through the second reheat valve 34-2, and only then into the expansiondevice 22.

In some embodiments, the second reheat valve 34-2 can be a check valvethat allows the refrigerant 42B to exit the reheat refrigerant circuit14 back into the cooling refrigerant circuit 12. In other embodiments,the second reheat valve 34-2 can be in electrical communication with thecontroller 30, which controls the second reheat valve 34-2 to the openposition during the defrost mode of operation to allow the refrigerant42B to reenter cooling refrigerant circuit 12.

The present disclosure has determined that the heat of the refrigerant42A (supplemented by the heat provided by the evaporator fan 28) can beused to defrost the evaporator 24 in the manner discussed in more detailbelow by simply reversing the direction of flow of the indoor air 50across the evaporator 24 from first direction 54 (FIGS. 1 and 2) tosecond direction 60 (FIG. 3).

Since the refrigerant 42A is flowing through the reheat coil 32 andindoor air 50 is forced in second direction 60, the indoor air 50 isheated by the refrigerant flowing through the reheat coil 32 into aheated indoor air 62, which is subsequently forced across the evaporator24.

Here, the reheat coil 32 acts as a heat rejecting heat-exchanger wherethe heat is transferred from the refrigerant 42A to the indoor air 50that is forced across the reheat coil 32 by the evaporator fan 28. Inthis manner, the indoor air 50 can be heated to a desired temperature sothat the heated indoor air 62 can melt any frost that has formed on theoutside surfaces of the evaporator 24.

In addition, the reheat coil 32 acts as a heat rejection heat-exchangerwhere during heat transfer interaction with the indoor air 50 so thatthe vapor refrigerant 42A is desuperheated to the point where itcondenses to liquid refrigerant 42B that is then typically subcooled, inthe case of a condenser, and is simply cooled to the thermodynamic state42B, in the case of a gas cooler. The expansion device 22 expandsrefrigerant 42B into a low pressure, low temperature two-phase mixturerefrigerant 48 and flows it into the evaporator 24. The evaporator 24acts as a heat accepting heat-exchanger where heat transfer interactionis taking place between the refrigerant 48 and heated indoor air 62 thatis forced across the evaporator 24 by the evaporator fan 28. In thismanner, the refrigerant 48 is evaporated back into a low pressure vaporrefrigerant 40, while the heated indoor air 62 is cooled to provide theair 64. The vapor refrigerant 40 then flows from the evaporator 24 backto the compressor 18.

Accordingly, during the defrost mode of operation for the refrigerantsystem 10, the controller 30 activates the compressor 18, deactivates,when necessary, the heat rejection heat-exchanger fan 26, opens, ifdesired, the bypass valve 36, opens the first reheat valve 34-1,controls, if necessary, the expansion valve 22, and causes theevaporator fan 28 to force the indoor air 50 across the evaporator 24and the reheat coil 32 in the second direction 60.

In the embodiment illustrated in FIG. 3, the refrigerant system 10 canforce the indoor air 50 in the second direction 60 by controlling theevaporator fan 28 to rotate in a second rotational direction 66, whichis opposite the first rotational direction 56.

It should be recognized that the refrigerant system 10 is describedabove by way of example providing the indoor air 50 in the first andsecond directions 54, 60 by changing the rotational direction of theevaporator fan 28 between the first and second rotational directions 56,66. Of course, it is contemplated by the present disclosure for therefrigerant system 10 to be configured in any manner to provide theindoor air 50 in the first and second directions 54, 60. It has to beunderstood that when the controller 30 operates the refrigerant system10 in the defrost mode and moves the indoor air 50 in the seconddirection 60, the air 64 exiting the evaporator 24 may be directedeither outdoors, indoors or to any other specified location.

It has to be recognized that the axial fans and transverse fans aremostly suitable for switching airflow direction, the former—by simplyswitching the rotational direction of the fan and the latter—byimplementation of a special design feature (typically, a lever) withinthe fan housing. The preferable design configuration for the centrifugalfans is described hereinbelow. Further, the design options and variousconfigurations of the refrigerant system 10 are feasible as well aswithin the scope and can equally benefit from the disclosure.

By way of example, an alternate embodiment of a configuration of therefrigerant system 10 that provides the indoor air 50 in the first andsecond directions 54, 60 is shown in FIGS. 4 and 5. Here, only portionsof the refrigerant system 10 are shown for purposes of clarity but airduct configuration is depicted in more detail.

In this embodiment, the controller 30 controls the evaporator fan 28 torotate in a single direction, such as the first rotational direction 56.Further, the controller 30 controls the position of one or more dampers70 to change the direction of the flow of indoor air 50 through theindoor components of the refrigerant system 10.

Thus, dampers 70 are positioned so that when the refrigerant system 10is in the normal mode of operation or the reheat mode of operation shownin FIG. 4, the indoor air 50 can be forced in the first direction 54 toresult in the indoor air 50 being forced first across the evaporator 24to form a conditioned air 52, which is then forced across the reheatcoil 32. In the normal mode of operation, the conditioned air 52 is notreheated by the reheat coil 32, which is disengaged, so that the cooledand typically dehumidified air 52 is provided to the conditionedenvironment in the manner discussed above. In the reheat mode ofoperation, the conditioned air 52 is reheated by the reheat coil 32 sothat reheated air 58 is provided to the conditioned environment in themanner discussed above.

Conversely, the dampers 70 are positioned so that when the refrigerantsystem 10 is in the defrost mode of operation shown in FIG. 5, theindoor air 50 can be forced in the second direction 60 to result in theindoor air 50 being forced first across the reheat coil 32 to form theheated indoor air 62, which is then forced across the evaporator 24 todefrost the evaporator.

It should be understood that the refrigerant system 10 is illustrated byway of example in FIGS. 4 and 5 reversing the direction of airflowthrough the use of four dampers 70. Of course, it is contemplated by thepresent disclosure for the refrigerant system 10 and associated air ductsystem including dampers 70 to have various configurations andadditional design features. All these configurations are within thescope and can equally benefit from the disclosure.

It should also be understood that the refrigerant system 10 exhibited inFIGS. 1 through 3 may have various options and enhancement features, allof which are contemplated within the scope of and can equally benefitfrom the present disclosure.

For example, the reheat refrigerant circuit 14 is illustrated inselective fluid communication with the cooling refrigerant circuit 12 ata location between the heat rejection heat-exchanger 20 and theexpansion device 22. However, it is contemplated by the presentdisclosure for the refrigerant system 10 to have any configuration ofthe reheat circuit 14 provided that the reheat coil 32 is positioneddownstream with respect to the flow of indoor air 50 induced by theevaporator fan 28 during the normal and reheat modes of operation.

It should also be understood that the terms “first”, “second”, “third”,“upper”, “lower”, and the like may be used herein to modify variouselements. These modifiers do not imply a spatial, sequential, orhierarchical order to the modified elements unless specifically stated.

While the present disclosure has been described with reference to one ormore exemplary embodiments, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of thepresent disclosure. In addition, many modifications may be made to adapta particular situation or material to the teachings of the disclosurewithout departing from the scope thereof. Therefore, it is intended thatthe present disclosure not be limited to the particular embodiment(s)disclosed as the best mode contemplated, but that the disclosure willinclude all embodiments falling within the scope of the appended claims.

1. A refrigerant system comprising: a cooling refrigerant circuitincluding a heat rejection heat-exchanger and an evaporator in serialfluid communication with one another; a reheat refrigerant circuitincluding a reheat heat-exchanger in selective fluid communication withsaid cooling refrigerant circuit; an evaporator fan being configured toforce indoor air in a first direction and in a second direction, theindoor air passing across said evaporator before passing across saidreheat heat-exchanger in said first direction and passing across saidreheat heat-exchanger before passing across said evaporator in saidsecond direction; and a controller being configured to operate therefrigerant system in one of a cooling mode and a defrost mode, whereinsaid controller, when the refrigerant system is in said cooling mode,controls said reheat refrigerant circuit so that said reheat refrigerantcircuit is at least partially isolated from said cooling refrigerantcircuit and controls said evaporator fan to force the indoor air in saidfirst direction, and wherein said controller, when the refrigerantsystem is in said defrost mode, controls said reheat refrigerant circuitso that said reheat refrigerant circuit is in fluid communication withsaid cooling refrigerant circuit and controls said evaporator fan toforce the indoor air in said second direction.
 2. The refrigerant systemof claim 1, wherein said controller is further configured to operate therefrigerant system in a reheat mode by controlling said reheatrefrigerant circuit so that said reheat refrigerant circuit is in fluidcommunication with said cooling refrigerant circuit and controlling saidevaporator fan to force the indoor air in said first direction,
 3. Therefrigerant system of claim 1, further comprising a heat rejectionheat-exchanger fan being configured to selectively force outdoor airacross said heat rejection heat-exchanger, said controller beingconfigured to control said heat rejection heat-exchanger fan not toforce said outdoor air across said heat rejection heat-exchanger, whenthe refrigerant system is in said defrost mode.
 4. The refrigerantsystem of claim 1, further comprising a bypass refrigerant circuit tobypass at least a portion of refrigerant around said heat rejectionheat-exchanger in selective fluid communication with said coolingrefrigerant circuit.
 5. The refrigerant system of claim 4, wherein saidcontroller controls said bypass refrigerant circuit so that said bypassrefrigerant circuit is at least partially isolated from said coolingrefrigerant circuit, when the refrigerant system is in said defrostmode.
 6. The refrigerant system of claim 4, wherein said controllercontrols said bypass refrigerant circuit so that said bypass refrigerantcircuit is in fluid communication with said cooling refrigerant circuit,when the refrigerant system is in said defrost mode.
 7. The refrigerantsystem of claim 1, wherein said controller controls a rotationaldirection of a fan motor driving said evaporator fan to force the indoorair in said first and second directions, respectively.
 8. Therefrigerant system of claim 1, wherein said controller controls aposition of one or more dampers with respect to said evaporator fan toforce the indoor air in said first and second directions, respectively.9. The refrigerant system of claim 1, wherein said evaporator fan is avariable speed fan.
 10. A refrigerant system comprising: a coolingrefrigerant circuit including an evaporator; a reheat refrigerantcircuit including a reheat heat-exchanger in selective fluidcommunication with said cooling refrigerant circuit; an evaporator fanbeing configured to rotate in a first rotational direction to forceindoor air in a first direction and configured to rotate in a secondrotational direction to force the indoor air in a second direction, saidevaporator being positioned upstream of said reheat heat-exchanger insaid first direction; and a controller being configured to operate therefrigerant system in a cooling mode, where said reheat refrigerantcircuit is at least partially isolated from said cooling refrigerantcircuit and said evaporator fan rotates in said first rotationaldirection and in a defrost mode, where said reheat refrigerant circuitis in fluid communication with said cooling refrigerant circuit and saidevaporator fan rotates in said second rotational direction.
 11. Therefrigerant system of claim 10, wherein said controller is furtherconfigured to operate the refrigerant system in a reheat mode, wheresaid reheat refrigerant circuit is in fluid communication with saidcooling refrigerant circuit and said evaporator fan rotates in saidfirst rotational direction.
 12. A refrigerant system comprising: acooling refrigerant circuit including an evaporator; a reheatrefrigerant circuit including a reheat heat-exchanger in selective fluidcommunication with said cooling refrigerant circuit; an evaporator fanbeing configured to rotate in a single rotational direction; one or moredampers being in a flow path of the indoor air, said one or more dampershaving a first position and a second position, said first position beingconfigured to force the indoor air in a first direction where the indoorair passes across said evaporator before said reheat heat-exchanger andsaid second position being configured to force the indoor air in asecond direction where the indoor air passes across said reheatheat-exchanger before said evaporator; and a controller being configuredto operate the refrigerant system in at least one of a cooling mode,where said reheat refrigerant circuit is at least partially isolatedfrom said cooling refrigerant circuit and said one or more dampers arein said first position and in a defrost mode, where said reheatrefrigerant circuit is in fluid communication with said coolingrefrigerant circuit and said one or more dampers are in said secondposition.
 13. The refrigerant system of claim 12, wherein saidcontroller is further configured to operate the refrigerant system in areheat mode, where said reheat refrigerant circuit is in fluidcommunication with said cooling refrigerant circuit and said one or moredampers are in said first position.
 14. A method of controlling arefrigerant system comprising: controlling a reheat refrigerant circuitso that said reheat refrigerant circuit is at least partially isolatedfrom a cooling refrigerant circuit and controlling an evaporator fan toforce indoor air in a first direction across an evaporator then across areheat heat exchanger, when the refrigerant system is in a cooling mode;and controlling said reheat refrigerant circuit so that said reheatrefrigerant circuit is in fluid communication with said coolingrefrigerant circuit and controlling said evaporator fan to force theindoor air in a second direction across said reheat heat exchanger thenacross said evaporator, when the refrigerant system is in a defrostmode.
 15. The method of claim 14, further comprising controlling saidreheat refrigerant circuit so that said reheat refrigerant circuit is influid communication with said cooling refrigerant circuit andcontrolling said evaporator fan to force the indoor air in said firstdirection, when the refrigerant system is in a reheat mode.
 16. Themethod of claim 14, wherein controlling said evaporator fan to force theindoor air in said first direction comprises controlling said evaporatorfan to rotate in a first rotational direction, and wherein controllingsaid evaporator fan to force the indoor air in said second directioncomprises controlling said evaporator fan to rotate in a secondrotational direction.
 17. The method of claim 14, wherein controllingsaid evaporator fan to force the indoor air in said first directioncomprises controlling said evaporator fan to rotate in a firstrotational direction and moving one or more dampers to a first position,and wherein controlling said evaporator fan to force the indoor air insaid second direction comprises controlling said evaporator fan torotate in said first rotational direction and moving said one or moredampers to a second position.
 18. The method of claim 14, furthercomprising controlling a heat rejection heat-exchanger fan not to forceoutdoor air across a heat rejection heat-exchanger, when the refrigerantsystem is in said defrost mode.
 19. The method of claim 14, furthercomprising at least partially isolating a bypass refrigerant circuitfrom said cooling refrigerant circuit, when the refrigerant system is insaid defrost mode.
 20. The method of claim 14, further comprisingplacing a bypass refrigerant circuit in fluid communication with saidcooling refrigerant circuit, when the refrigerant system is in saiddefrost mode.